1. Field of the Invention
The present invention relates to a method for fabricating a power metal-oxide-semiconductor field effect transistor (MOSFET), and more particularly, to a method for fabricating a trench power MOSFET.
2. Description of the Related Art
Power metal-oxide-semiconductor field effect transistor (MOSFET) is a type of high voltage device that can operate at a voltage of about 4500V and upwards. The conventional method of fabricating the power device is very similar to the fabrication of common semiconductor devices. The gate of the power device is formed on the surface of a silicon substrate in the so-called planar gate fabrication method. However, this type of planar gate structures has the disadvantage of being limited by the design of a required smallest gate length. In other words, it is difficult to increase the packing density of devices.
As a result, a trench type fabrication method has been developed to significantly decrease the dimension of the power devices. Accordingly, the trench gate fabrication has become the trend for manufacturing power devices.